This invention pertains to the field of liquid crystal displays, and more particularly to a liquid crystal cell that can be utilized in displays.
Present nematic liquid crystal displays are primarily field-effect devices which lack memory, and thereby suffer from stringent multiplexing limitations imposed by refresh requirements. A persistent electrooptic response requiring no sustaining voltage is desirable for large area display applications. Although memory effects have been discovered in smectic and cholesteric materials, these effects are mostly based on the thermodynamic metastability of ordered and disordered textures of the mesophase, and often require thermal transitions through an intermediate isotropic phase.
Purely electrically driven memory effects are rare, existing only in some special smectic materials associated with the generation of defects or electrohydrodynamic instabilities, and in rate-controlled electrical switching of positive cholesterics.